Lockstitch shoe sewing machines



March 6, 1956 F AsHwoRTH Er AL LOCKSTITCH SHOE SEWING MACHINES Filed Feb. 9, 1954 5 Sheets-Sheet l Inventors Fred flshworh, Jose/oh i? loan/11'! By zhez'rflorney March 6, 1956 F. AsHwoRTH Er AL 2,737,134

v LocxsTITcH sHoE SEWING MACHINES Filed Feb. 9, 1954 'sweets-sheet 2 Inventors 'Fred Ash worzfh March 6, 1956 F. A'sHwoRTH Er AL 2,737,134

LOCKSTITCH SHOE SEWING MACHINES Filed Feb. 9, 1954 3 Sheets-Sheet 3 United States Patent O LOCKSTITCH SHOE SEWING MACHINES Fred Ashworth, Wenham, and Joseph R. Ioannill, Beverly, lMass., assignors to United Shoe Machinery Corporation, Flemington, N. J., a corporation of New Jersey Application February 9, 1954, Serial No. 409,152

2 Claims. (Cl. 112-36) The present invention relates to shoe sewing machines and more particularly to improvements in a hook needle locksttch machine of the McKay type having a rotary shoe entering horn, and a shuttle arranged when engaging each loop of needle thread to draw the preceding loop towar-d the work and to set the stitch formed by the preceding loop. A machine of this type is disclosed in United States Letters Patent No. 2,670,701, granted March 2, 1954, in the names of the present inventors.

The machine disclosed in the patent above referred to has a hook needle supported for oscillation on a swinging carrier arm, which needle has only a slight curvature so that exure is at a minimum when resistance to penetration is met in sewing hard, stiff work. If a needle of even slight curvature is employed upon work of great ly increased thickness or unusual toughness, however, exure eventually becomes so excessive as to be prohibitive. It is then necessary toresort to the use of a straight needle supported on one end of a reciprocating needle bar. In the use of a straight reciprocating needle supporting bar the inertia of parts connected to the needle is greater than is met with a curved needle secured to an oscillating supporting arm, so that mechanism suitable for reciprocating a straight needle ordinarily is not as desirable mechanically as that for oscillating a curved needle, the reciprocating mechanism being subject to excessive stresses, substantially reducing its durability and limiting its speed of operation.

The machine of the prior patent also has a work penetrating awl acting from the same side of the work as the needle so that the needle is not required to form its own perforations in the work. However, when a machine is constructed to operate upon extremely thick work, for instance thicker than one inch, a longer time is required to reciprocate the needle and awl through their full strokes, all other things being equal. The time of each sewing cycle, therefore, taken up by the reciprocating movements of the needle and awl greatly reduces the remaining time available for other operations required in the machine.

In the machine of the prior patent the needle and awl are actuated by mechanisms with which the required movements are imparted through the use of cams having grooves of proper curvatures. With the use of cams accurate long stroke movements are easily obtainable but the forces of acceleration produced at high speed with straight needle reciprocatingparts reach an intensity substantiallygreater than an ordinary cam is able to support. The only alternative for a high .speed long stroke straight needle shoe sewing machine accordingly is to employ suitable crank actuated needle and awl reciprocating mechanisms, the arrangement of which is subject to additional diiculties in obtaining the required accuracy of movements for theparts withinthe space and time available.

A further diiculty met in the machine of the patent referred to results from the use of a loop taker arranged 2,737,134 Patented Mar. 6, 1956 to engage simultaneously with two loops of needle thread to draw one loop of thread toward the work and to set the stitch being formed therewith by enlarging the other loop. The use of a loop taker of this type necessitates still more complicated restrictions in the timing of the needle and awl movements both in their stitch forming functions as well as in the` time allowable for feeding the work, especially where the needle acts as a work feeding instrument.

The objects of the present invention are to provide relatively simple and effective crank actuated needle and awl mechanisms in a shoe sewing machine, which overcome the difliculties of the prior mechanisms referred to and'which enable the use of a straight hook needle, a straight awl, and a loop taker arranged to engage two loops of needle thread simultaneously. To meet the requirements the needle and awl mechanisms must be suflicient rigid and durable to resist the forces of acceleration required in reciprocating the needle and awl effectively through strokes of unusual lengths suicient to sew work of a thickness greater than one inch at speeds equal to those employed in present lday shoemaking practices.

In the accomplishment of the objects noted above a shoe sewing machine of the type referred to is provided having a straight work feeding hook needle, a straight awl, a loop taker arranged when engaging each loop of needle thread to draw the preceding loop toward the work and to set the stitch formed by the preceding loop, and a carrier shiftable in the direction of work feed for mounting the needle and awl for reciprocation, in which the needle is actuated by a mechanism comprising a pitman connected with a crank at one end and tted with a wrist pin at its other end, a floating link connected to the wrist pin, a radius arm pivotally connected to the pitman at a point other than that at the axis of the wrist pin, a second radius arm pivotally connected to the floating link at a pointother than that at the axis of the wrist pin, a third radius arm connected to the floating link at a point other than those at the axis of the wrist pin and at the pivot axis connecting the second radius arm, and connections between the third radius arm and the needle to provide periods of dwell at both ends of the needle stroke and an additional one a short distance from the work penetrating end of its stroke, with rapid movements between the Idwells suicient to co-operate with requirements of other stitch forming devices. The additional dwell in the needle stroke is to provide time for the work feeding wrist pin on the awl pitman at one point along the lever,

a link connected to another point spaced along the awl lever from the first point, and 'connectionsbetween the awl link and the awl to provide a dwell at that end of the awl stroke in which the awl is disengaged from the work. By the use of the described crank and link actuated mechanisms for the needle and awl greater durability is obtainable where the strokes of the needle and awl are lengthened to accommodate extremely heavy work, greater than an inch in thickness, while operating at speeds commensurate with present day sewing practices.

These and other features of the invention, hereinafter described and claimed, will become apparent from-the following detailed specification, taken in connection with the accompanying drawings, in which Fig. 1 is a perspective view looking from the right front of a McKay type locksttch shoe sewing machine,

showing those portions of the machine in which the features of the present invention are embodied;

Fig. 2 is a detail view of certain devices and work engaging parts in the machine of Fig. l, illustrating the relationship of the parts while a loop of thread after being drawn through the work by the needle is expanded and the preceding loop of thread is drawn toward the Work by the shuttle;

Fig. 3 is a detail perspective view on an enlarged scale, looking from the right front of the machine and illustrating a feed carriage in which the needle and awl reciprocating bars are mounted;

Fig. 4 is a fragmentary perspective view of the needle and awl actuating mechanisms embodied in the machine of Fig. l;

Fig. 5 is a detail view in front elevation of the awl actuating mechanism; and

Fig. 6 is a similar View of the needle actuating mechanism.

The illustrated machine is similar, except as hereinafter pointed out, to the lockstitch McKay horn type shoe sewing machine disclosed in our prior patent above referred to. The stitch forming devices of the machine include a needle 2, an awl 4 and a multiple-beak shuttle 6. Instead of employing a curved awl and a curved needle as in the prior machine, the illustrated awl and needle are straight and are mounted for reciprocation toward and from the tip of a rotatably mounted shoe entering horn 8. The horn is rotatable about a vertical axis intersecting the horn tip in which is provided a needle threading looper or whirl (not shown) beneath a needle receiving opening 10 at the tip of the horn. Cooperating with the horn to clamp the work is a presser foot 9 (Fig. l). The shuttle 6 is similar to that of the prior patent except that there are five needle loop entering beaks instead of four as in the shuttle of the patented machine. The arrangement of the stitch forming devices is such that after engaging a loop of thread with a shuttle beak it is expanded and contracts a preceding loop of thread, still engaging the shuttle, drawing the preceding loop toward the work eventually to a position where the stitch formed thereby is securely set within the work. Referring to Fig. 2 of the drawings, one beak 13 of the shuttle 6 is shown expanding a loop 14 of thread while a preceding loop engaging a shuttle beak 16 is being contracted.

As in the prior machine, the work is fed by the needle a stitch length during each sewing cycle. The operations of the needle and awl correspond with those described in 'the prior patent, the awl entering the work and needle opening 1t) in the horn along the axis of horn rotation to penetrate the work. After withdrawing from the work, the awl is shifted laterally in a direction opposite to that of work feed and the needle is brought into alinement with the perforation made by the awl. The needle then is actuated quickly through the awl perforation in the work and enters the opening 10 in the horn to receive a loop of thread in its hook. It then retracts to a vertical position where its threaded hook stops momentarily just clear of the needle opening in the horn. During its momentary stop the needle moves laterally in the direction of work feed with the work a distance equal to the length of a stitch. After moving with the work a stitch length the needle retracts entirely from the work, the loop carried thereby being brought into engagement with a beak on the shuttle. Thus, while disengaged from the work the needle dwells in its highest position as each stitch is being set and immediately thereafter the awl forms a perforation in the work for a new stitch. The needle then moves rapidly into the awl perforation in the work where it dwells a second time while a loop is being laid in its hook. After reti-acting to bring its threaded hook into the Work it dwells momentarily a t'nird time while the Work is being fed.

The awl has but one period of dwell, while disengaged from the work, its movements toward and from the work being as rapid as possible. The needle, however, has three periods of dwell, one at each end of its stroke and an additional one a short distance from the lower work penetrating end of its stroke after drawing its threaded hook into the work to a position clear of the horn while feeding the Work.

For actuating the needle and awl, they are secured in the lower ends of reciprocating needle and awl bars 17 and 13, respectively. These bars are of rectangular cross section and are retained for sliding movement within a box-like carrier 20, having at its lower end a pair of rearwardly extending lugs having secured in them a horizontal rod 22 slidingly mounted within a main frame 24 of the machine. Near its upper end the carrierhas an additional pair of rearwardly extending lugs slidingly mounted on a bar 26 xed in the main frame 24. For actuating the carrier 2@ in the direction of feed, indicated by the arrow in Fig. 3, to feed the work and to bring the needle and awl into alinement with the horn axis at the proper times in each sewing cycle, the carrier has pivotally connected to it a horizontal link 28 also connected to a pin 30 passing through a pair of links 32 and 34 disposed approximately at right angles to each other. The link 32 is pivotally connected to a horizontal arm 36 secured to one end of a rockshaft 38, the other end of which has fixed to it a cam lever provided with a roll 42 engaging a cam on a main sewing shaft 44 (see Figs. l and 4). The link 34 has, passing through its end opposite the pin 36, a clamp bolt 4S extending through an arcuate slot in an arm 46. The arm 46 is formed integrally with a sleeve 47 rotatably mounted in the machine frame and surrounding the rockshaft 38. The sleeve 47 has clamped to it an arm 48 carrying a roll 50 engaging a cam on the shaft 44. Both the cam arms 40 and 48 are thus connected to the feed carrier 20, one being adjustably connected to regulate the length of stitches inserted by the machine and the other being nonadjustably connected to bring the needle and awl into proper alinement with the opening 10 in the horn during the work penetrating strokes thereof.

The illustrated machine is intended for operation upon work having a maximum thickness of at least one and one-quarter inches, which is greatly in excess of the usual thickness of work capable of being operated upon by the machine disclosed in the prior patent. It has been found that with work of such unusual thickness it is necessary to employ a straight needle and a straight awl in place of the curved needle and awl utilized in the patented machine, the needle and awl bars 17 and 18 being of sufficient length to accommodate reciprocating movement in the needle and awl of over two inches. To enable the needle and awl bars 17 and 18, of the machine embodying the present invention, to be reciprocated through their two inch ranges of movement smoothly and rapidly without subjecting the actuating mechanisms therefor to excessive wear, these mechanisms are driven by first and second cranks 51 and 52 formed on the main sewing shaft 44.

Referring to Figs. 4, 5 and 6 the needle and awl actuating cranks 51 and 52 consist of pins mounted eccentrically of the shaft 44, each of which pins have their ends secured between two of three disks 53 xed to spaced sections of the shaft 44. To provide the required overall stroke, rapid motion for the needle and necessary dwells, the crank 51 is engaged with one end of a triple pivoted pitman 54 and the other end of the pitman is litted with a wrist pin 56 formed with a ball head engaging a socket in one end of a floating link 58. For retaining the wrist end of the pitman in a predetermined path of movement it is pivotally connected at a point 60 with a rst radius arm 62, the point of pivot connection with the pitman being spaced from the axis of the wrist pin 56. The radius arm 62 is rotatably mounted on a xed stud 64 carried by the main frame.

To control the movements of the floating link 58 it is pivotally connected at a point 66 to a second radius arm 68, the point 66 being spaced along the oating link from the axis of the wrist pin 56. The motion of the floating link 58 is determined by the wrist pin 56 and the radius arm 68, which is pivotally connected through a link 69 extending between the pin 66 and a pivot point 70 on a third radius arm 72. Theconnection point 70 between the third radius arm 72 and the link 69 is spaced from both of those connecting the oating link with the wrist pin 56 on the pitman and the pivot connection with the second radius arm 68, the point 66 being movable into line with the wrist pin 56 and the point 70. The radius arm 68 is rotatably mounted on a fixed stud 74 and the third radius arm 72 is secured to a rockshaft 76 rotating in bearings in the frame 24.

The fixed studs 64 and 74 and rockshaft 76 are located, as shown in Fig. 6, so that the crank 51, while moving in the direction of the arrow, causes the wrist pin 56 and the point 66 to move into line with center of the rockshaft 76. As these parts move into line there is a dwell in the needle in its highest position. While the thread is being laid in the needle hook the stud 64 and the wrist pin 56 come into line with the stud 74. While the needle is feeding the work the third dwell occurs after the line connecting the stud 64 and the pin 56 moves beyond the stud 74 and again returns into line with it.

To transfer the motion produced by the needle actuating mechanism to the needle suitable additional connections are provided. The rockshaft 76 has secured to it an arm 78 pinned to the shaft, a link 80 pivotally connected to the arm and to the upper end of the needle bar 17. With the mechanism and connections thus described the needle 2 at the lower end of the bar has imparted to it, suciently rapid movements between the ends of its stroke, and periods of dwell for proper cooperation with the awl, shuttle and other stitch forming devices when operating with a two inch stroke upon work at least one and one-quarter inch in thickness.

The awl actuating mechanism includes the second crank 52, a second pitman 82 connected with the crank at one end, and pivotally connected at its other end to a second wrist pin 84, the pitman 82 having a socket surrounding a ball head on the wrist pin. The wrist pin 84 is clamped to an awl actuating lever 86 at an intermediate point along the lever. The lever 86 is fulcrumed on a stud 88 secured in the machine frame. At another point 90 along the length of the awl actuating lever 86 on the end opposite its fulcrum beyond the wrist pin is a pivot forming a connection with a link 92 in turn connected with the awl.

The connections between the link 92 and the awl are such that the awl actuating mechanism provides a dwell at that end of the awl stroke in which the awl is disengaged from the work. These connections include an arm 94 pivotally connected to the link 92 and secured to a rockshaft 96, an arm 98 also secured to the rockshaft 96 and pivotally connected to one end of a link 100, the other end of which is pivotally connected to the awl bar 18. At that end of the awl stroke in which the awl is disengaged from the work the link 92 and the lever 86 which comprise a toggle have their central joint brought into line with the pivots at their opposite ends to produce the desired dwell while the awl is disengaged from the work. This dwell in awl motion occurs also while the needle engages the work.

To assist in imparting to the needle and awl bars the requisite motion at usual present day sewing speeds, the pivotal connections between the links, arms and levers are of the ball and socket type disclosed in a copendng application for United States Letters Patent Serial No. 349,872, filed April 20, 1953 in the names of the present inventors.

The nature and scope of the invention having been set forth and a particular embodiment described, what is claimed is:

l. A shoe sewing machine having a sewing shaft, stitch forming and work feeding devices including a straight hook work feeding needle and a straight awl, a work support, a loop taker arranged when engaging each loop of needle thread to draw the preceding loop toward the Work and to set the stitch formed by said preceding loop, and a carrier shiftable in the direction of work feed in which the needle and awl are mounted for reciprocation, in combination with mechanism for reciprocating the needle toward and from the work, comprising a crank on the sewing shaft, a pitman connected at one end with the crank, a wrist pin tted to its other end, a floating link connected to the wrist pin on the pitman, a first radius arm also connected to the pitman at a point spaced from the axis of the wrist pin, a second radius arm pivotally connected to the tloating link, a third radius arm, a connecting link between the third radius arm and the oating link, and connections between the third radius arm and the needle to provide periods of dwell at both ends of the needle stroke and an additional dwell a short distance from the work penetrating end of its stroke to provide time for work feeding movement.

2. A shoe sewing machine having a sewing shaft, stitch forming and work feeding devices including a straight work feeding hook needle and a straight awl, a work support, a loop taker arranged when engaging each loop of needle thread to draw the preceding loop toward the work and to set the stitch formed by said preceding loop, and a carrier shiftable in the direction of work feed in which the needle and awl are mounted for reciprocation, in combination with mechanism for reciprocating the needle toward and from the work, comprising a crank on the sewing shaft, a pitman connected at one end with the crank, a wrist pin ttted to its other end, a floating link connected to the wrist pin on the pitman, a rst radius arm mounted on a fixed stud and also connected to the pitman at a point spaced from the axis of the wrist pin, a second radius arm mounted on a Xed stud and pivotally connected to the oating link, a third radius arm, a connecting link between the third radius arm and the floating link to move the wrist pin into line with the fixed studs, and other connections between the third radius arm and the needle to provide periods of dwell at both ends of the needle stroke, and mechanism for reciprocating the awl toward and from the work, comprising a second crank on the sewing shaft, a second pitman connected with the second crank at one end, a wrist pin tted to the other end of the second pitman, a lever connected with the second wrist pin on the awl pitman at one point along said awl wrist pin lever, a link connected to an intermediate point along the awl wrist pin lever, and connections between the awl lever connected link and the awl to provide a dwell at that end of the awl stroke in which the awl is disengaged from the work and the needle engaged with the work.

References Cited in the le of this patent UNITED STATES PATENTS 

